This invention relates to a multi direction changeover or switchover mechanism used in a speed changer for an automotive vehicle or various switch mechanisms.
In a running game machine, a multi change gear system or a shift lever system is provided in a driver's compartment, and an operator (driver) operates an operation lever of the shift lever system to change a running speed of the game machine at a desired value. Thereby, the operator simulatively drives the running machine at the desired speed and enjoys driving.
The shift lever system has a shift plate formed with speed range setting grooves oriented in the lengthwise and widthwise directions over the plate. A neutral zone is defined in an intermediate portion of the speed range setting grooves through which an operation lever stands upright. The operator selects a desired speed range groove among the grooves and shifts the operation lever in a direction toward the selected speed range groove to fit the operation lever in the selected groove. When the operation lever is securely shifted and fitted in the selected groove, the speed of the running machine is changed to a desired speed in the selected speed range.
A multi directional shift mechanism is adopted in the above mentioned multi gear or shift lever system. The multi directional shift mechanism is not only adopted in the shift lever system but also applied to an electric switch circuitry or its equivalent in which a desired circuit is selected from among plural branch circuits.
In order to move the operation lever in the desired direction over the shift plate, the operation lever is required to be securely supported on the shift plate to be movable in the desired direction. To secure the support of the operation lever, there have been proposed several arrangements, as disclosed in Japanese Unexamined Patent Publication HEI No. 8-117442 and HEI No. 7-281590.
The former publication has the arrangement in which a spherical portion is formed at a position corresponding to the center of a pivotal rotation of an operation lever, and this spherical portion is supported by a stem member. The latter publication employs a dual-axis system in which an operation lever is pivotally supported in a box formed with a vertical through hole. Specifically, the operation lever is pivotally supported about a first axis which horizontally extends in the box, and is also pivotally supported about a second axis which horizontally extends in the box in a direction different from the extending direction of the first axis.
In the arrangement of the former publication, production of the spherical portion itself is difficult, and the operation lever including the spherical portion and the stem portion is also difficult. Also, a click mechanism for informing an operator that the operation lever has been securely set to a desired speed range becomes complex, resulting in raising the production cost of the multi directional shift mechanism.
In the arrangement of the latter publication in which the operation lever is pivotable about the two axes in the box, at least two bias force suppliers which respectively apply a biasing force to the operation lever are required to return the operation lever to the neutral zone. Accordingly, the bias force supply mechanism itself becomes complex, thereby raising the production cost of the multi directional shift mechanism.